The present invention is directed to machines for laser processing of workpieces, and more particularly, to such machines which utilize a laser beam for cutting, welding and the like and which provide means for alignment of mirrors in a beam transmission system therein.
Lasers are now fairly widely employed in apparatus for the processing of workpieces such as, for example, in cutting, welding, heat treating and the like. As is well known, the extraordinarily narrow laser beam can be used to cut parts of various shapes from a workpiece and to cut small openings within a part. Moreover, the holes cut through the part can be spaced be especially adapted to the manufacture of unique products, or small runs of products, with fairly complicated configurations through the use of suitable control mechanisms to control either the motion of the laser cutting head or the motion of the workpiece on a support table beneath the laser cutting head, or both. By changing the program in the numeric control system for the laser apparatus, the workpiece and the orientation of the various cutting operations to produce the desired part can be readily altered.
Some laser processing machines utilize a table upon which the workpiece is supported, and the workpiece is held by clamping jaws or like mechanisms and moved about the support table in X and Y directions by suitable X-Y drive mechanisms which are controlled by a computer or like control system. In still other machines, the workpiece is supported in a fixed position upon the table, and the laser head is supported for movement in X-Y directions relative to the workpiece. When the workpiece itself is being moved, frequently a relatively large mass must be moved and stopped in a precise manner. In either type of apparatus, the laser beam must be focused so as to impinge upon the workpiece at a predetermined spot.
As it well known, most laser generators include a plurality of mirrors which direct the light rays back and forth until the laser beam of desired intensity has been developed. The laser beam then exits the laser generator through a suitable shutter mechanism.
In most equipment for laser processing of workpieces, there is an optical beam transmission system providing the pathway between the output of the laser generator and the laser beam focusing head wherein the laser beam is focused by lenses to the desired point upon the workpiece. These optical transmission systems include at least one and generally several mirrors which alter the direction of travel of the laser beam and ultimately direct the laser beam into the optics of the laser beam focusing head. As is also well known, misalignment of the mirrors in this optical beam transmission system will seriously affect the power delivered to the workpiece and can in fact, cause damage to the apparatus if the beam is misaligned sufficiently to impinge upon elements of the apparatus. Accordingly, one or more mirrors within the system is usually adjustable in order to effect their realignment from time-to-time to ensure that the laser beam is transmitted along its optimum path to the focusing lens system.
In practice, it has been customary to switch the laser generator on for a short period of time and to observe the point of impingement upon a workpiece or target and then to effect such adjustment of the mirror or mirrors as is necessary to precisely align the beam exiting from the laser beam focusing head in the proper position upon the workpiece or target. Generally, this requires that the laser beam be one which is in the visible spectrum, or, when the main beam used for the laser processing of the workpiece is in the invisible or infrared range, the provision of a second beam within the visible range travelling in a parallel path. This is frequently the case with carbon dioxide lasers used for most high powered industrial applications.
As will be appreciated, industrial lasers, and particularly those used in connection with the processing of heavy workpieces, will be subject not only to vibrations and shocks generated within the apparatus itself, but also to ambient vibrations and shocks from adjacent equipment. Thus, from time-to-time, it may be necessary to effect realignment of the mirrors in the beam transmission system in order to keep the laser operating efficiently and in precise alignment with the X-Y guidance system used for moving either the laser cutting head or the workpiece.
It is an object of the present invention to provide novel laser apparatus for performing operations upon a workpiece in which misalignment of the laser beam may be readily determined and the deviation of the laser beam from its optimum pathway may be readily corrected.
It is also an object to provide such apparatus in which the correction may be effected automatically through precision control mechanisms for one or more mirrors in the beam transmission system.
Another object is to provide such apparatus which is simple and effective for laser beams in the invisible spectrum.
A further object is to provide a method for laser processing of workpieces in which precise and simple adjustment of one or more mirrors in an optical beam transmission system may be effected to correct any deviation of the laser beam from its optimum path to the laser beam focusing head.